Which of the following statements can be inferred from the passage？
A. Improvements in sanitation are a vital element in helping ward off peptic ulcers.
B. People in the developing countries are not likely to contract esophageal diseases.
C. Nowadays few people in the developed countries suffer from stomach cancer.
D. Scientists have long recognized H. pylori's important role in the stomach, but could do nothing about it.
微信支付 
支付宝支付